Instead of sewing them together I use zip ties for the middle. You can get a pack of 100 for about $1.00-2.00 at any hardware store or wal-mart. They hold the bow together perfectly! With the thicker ribbon (layers and layers) use a pair of pliers to pull the zip tie tight.

You know, come to think of it I did end up using zip ties at the end of my last squad last summer. I had totally forgotten about doing that. Thanks so much for the reminder!! I used a clipboard in my lap, got my center creased how I like it on my strong embroidery needle wrapped a zip tie and then used my pliers to pull the small, clear zip tie tight.